1. Technical Field
The present invention relates to a liquid-ejecting head that ejects a liquid from a nozzle opening; a liquid-ejecting apparatus; and a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode.
2. Related Art
Piezoelectric elements used for liquid-ejecting heads each include two electrodes and a piezoelectric layer composed of a piezoelectric material having an electromechanical transducing function such as a crystalline dielectric material, the piezoelectric layer being sandwiched between the two electrodes. Such piezoelectric elements are used as actuators that operate in a flexural vibration mode and are mounted in liquid-ejecting heads. Typical examples of the liquid-ejecting heads include ink jet recording heads including diaphragms that form portions of pressure-generating chambers communicatively connected to nozzle openings from which ink droplets are ejected. The diaphragms are distorted with piezoelectric elements such that ink contained in the pressure-generating chambers is pressurized, whereby the ink is ejected from the nozzle openings as droplets. For example, the piezoelectric elements mounted in the ink jet recording heads are produced so as to independently correspond to pressure-generating chambers by uniformly forming a piezoelectric material layer over the entire surface of the diaphragms using a film formation technique and cutting the piezoelectric material layer into sections having a shape corresponding to that of the pressure-generating chambers by lithography.
A metal oxide having a perovskite structure such as lead zirconate titanate (PZT) is used as a piezoelectric material for such piezoelectric elements (refer to JP-A-2001-223404).
However, when a high voltage is applied to such piezoelectric elements, current leakage is sometimes caused. The current leakage poses a problem in that piezoelectric elements are heated and broken and thus degraded. Such a problem is seen in not only ink jet recording heads but also liquid-ejecting heads that eject a liquid other than ink. Furthermore, the problem is seen in not only piezoelectric elements used for the liquid-ejecting heads but also piezoelectric elements used for other devices.